Rheological properties of bioinks for printing optimisation

3D bio-printing is a rapidly growing technique that aims to combine engineering principles and life sciences for the fabrication of in-vitro tissue, organs, and other biological constructs by utilising biomaterial-based scaffolds and living cells, in a layer-by-layer process. The fabrication of scaffold-based in-vitro models requires an architectural platform like the native extracellular matrix that provides structural support and aids in cellular proliferation and migration in the form of a bioink. Fabrication of bioinks for extrusion-based 3D bio-printing is challenging in achieving complex tissue structures. The rheological properties of bioinks determine the printability, structural fidelity, in turn depicting the viability of the cells during the printing process. Ideal bioinks should possess non-Newtonian characteristics such as shear-thinning during printing followed by quick structural recovery. Hydrogels are an appealing scaffold because they inherit natural biomimicry properties similar to the extracellular matrix of many tissues. Here, quantitative rheological assessments studying the relationship between stress (stimuli) and strain (response) of Alginate and Gelatin were explored to determine the flow behaviour and deformation to establish printing parameters. The results display low shear induced flow-behaviour properties with ideal viscosities that are desirable in preventing shear stress-caused damage to cells. This rheological study provides a predictive tool to understand the relationship between the material and its attributes displayed to optimise printing parameters which in turn can easily aid in the development of bioinks.